1. Field of the Invention
The present invention relates to a focus adjustment device and an imaging device.
2. Description of the Related Art
A focus adjustment device is heretofore known in which focus evaluation values regarding contrast of images by an optical system are obtained while search driving a focus lens thereby to detect focus statuses of the optical system. For example, Patent Document 1 (unexamined Japanese Patent Publication No. 2008-249966) suggests a technique in which the manner of search driving for the focus lens is varied at the time of obtaining the focus evaluation values depending on the focal distance of the optical system. More specifically, in the Patent Document 1, when the focal distance of the optical system is relatively large, a focus adjustable range of the optical system is determined as being also relatively wide, and it is attempted to reduce the required time for search driving by performing a first search driving in which the search driving is performed with a focus adjustable speed and then performing a second search driving of which the search speed is larger than that of the first search driving. On the other hand, when the focal distance of the optical system is relatively small, the focus adjustable range of the optical system is determined as being also relatively narrow, and a configuration is employed such that only the first search driving is performed in which the search driving is performed with the focus adjustable speed, because in this case the second search driving with the faster search speed is not necessary to be performed.